The 3GPP LTE (3rd Generation Partnership Project, Long Term Evolution) systems are systems which use radio access technology for packet-switched services. In similarity to other cellular systems, LTE systems comprise a number of cells, each of which can accommodate a number of users, and there is a controlling node for each cell, in LTE known as the eNodeB, “evolved NodeB”. Traffic from the eNodeB to the users is referred to as down link (DL) traffic, and traffic from the users to the eNodeB is referred to as up link (UL) traffic.
The LTE systems do not use dedicated channels, which means that all data in down link and up link is transmitted in shared channels, which in turn means that each user, also sometimes referred to as UE, “User Equipment”, needs to be scheduled in time and frequency in order to be able to receive and transmit data. The scheduling of the UEs in an LTE cell is carried out by the eNodeB of that cell.
Up link traffic in LTE is sent in so called sub frames, with each sub frame having, at present, a duration of 1 ms, and comprising a number of carrier frequencies, so called sub carriers. Thus, an LTE sub frame has an extension both in frequency and in time. In time, the LTE sub frame's 1 ms is divided into slots.
In LTE, there is a control channel known as the Physical Uplink Control Channel, abbreviated as PUCCH. The PUCCH is UE specific, and multiple PUCCHs can exist in parallel.
The UEs use the PUCCH in order to transmit control information such as, for example, the Channel Feedback Report, CFR, Hybrid Automated Repeat Request/Acknowledge, HARQ/ACK, and scheduling requests to the eNodeB of the cell.
The PUCCH is sent in the LTE sub frames, and is allotted a number of so called Resource Blocks, RBs, within a sub frame. An RB comprises a number of sub carriers and time slots within a sub frame, where the maximum number of sub carriers and time slots occupied by an RB obviously being limited by the number of sub carriers and time slots in a sub frame.
As can be realized, the amount of resources, i.e. RBs, needed for PUCCH for a UE will vary with a number of factors, such as, for example, the number of active UEs in the cell, which will influence the amount of CFR reports sent. Examples of other influencing factors are the traffic volumes in the down link and the uplink.
At present, there is no satisfactory mechanism in LTE for fitting the amount of PUCCH resources, i.e. RBs, which are allotted to a UE to the needs of the UE. One obvious mechanism would be to set the number of RBs for a UE to a fix value. However, this would cause a number of problems, such as, for example, the following:                In cases with a small number of UEs in a cell, and consequently few UEs transmitting control signals such as CFR, HARQ-ACK or scheduling request in each subframe, the PUCCH resources would be over-dimensioned, which would lead to a waste of uplink bandwidth, since some of the RBs allotted to PUCCH could be used for data traffic instead.        In cases with many UEs in a cell, and with many UEs using services with low bandwidth that are multiplexed in the same downlink subframe, the PUCCH resources would risk becoming a bottleneck that would prevent efficient downlink resource usage for data traffic.        